The business of manufacturing and marketing disposable absorbent articles for personal care or hygiene (such as disposable diapers, training pants, adult incontinence undergarments, feminine hygiene products, breast pads, care mats, bibs, wound dressing products, and the like) is relatively capital intensive and highly competitive. To maintain or grow their market share and thereby maintain a successful business, manufacturers of such articles must continually strive to enhance their products in ways that serve to differentiate them from those of their competitors, while at the same time controlling costs so as to enable competitive pricing and the offering to the market of an attractive value-to-price proposition.
One way in which some manufacturers may seek to enhance such products is through enhancements to softness. Parents and caregivers naturally seek to provide as much comfort as they can for their babies, and utilizing products such as disposable diapers that they perceive as relatively soft provides reassurance that they are doing what they can to provide comfort in that context. With respect to other types of disposable absorbent articles that are designed to be applied and/or worn close to the skin, perceptions of softness can reassure the wearer or caregiver that the article will be comfortable. Thus, the manufacturer of such articles may devote efforts toward enhancing the softness attributes of the structure of an article and of the various materials used to make the article, including the outermost materials of the article (e.g. materials that are visible and/or exposed to the wearer's skin or touch).
It is believed that humans' perceptions of softness of an absorbent article can be affected by tactile signals, auditory signals and visual signals.
Tactile softness signals may be affected by a variety of the article components' features and properties that have effect on its tactile feel. For example, many absorbent articles have outermost layer components formed of nonwoven materials, and attributes of such materials including but not limited to loft, fiber shape, thickness and density, basis weight, microscopic pliability and flexibility of individual fibers, macroscopic pliability and flexibility of the nonwoven web as formed by the fibers, surface friction characteristics, number of loose fibers or free fiber ends, and other features, may impact the tactile signals the article conveys.
Perceptions of softness also may be affected by auditory signals, e.g., whether and to what extent the materials of the article make audible rustling, crinkling or other noises when touched or manipulated.
It is believed that perceptions of softness of a material also may be affected by visual signals, i.e., its visual appearance. It is believed that, if materials forming an absorbent article look relatively soft to a person, it is much more likely that the person will perceive the article as having relative tactile softness as well. Visual impressions of softness may be affected by a variety of features and properties, including but not limited to color, opacity, light reflectivity, refractivity or absorption, apparent thickness/caliper, fiber size and density, and macroscopic physical surface features.
As a result of the complexity of the mix of the above-described characteristics and the subjective nature of individual perceptions, to the extent softness is considered an attribute of an absorbent article, it may elude precise measurement or quantification. Although several methods for measuring and evaluating material features that are believed to affect softness signals have been developed, there are no standard, universally accepted units or methods of measurement for softness. It is a subjective, relative concept, difficult to characterize in an objective way. Because softness is difficult to characterize, it can also be difficult to affect in a predictable way, through changes or adjustments to specifications in materials or manufacturing processes.
Complicating efforts to define and enhance softness is the fact that differing individuals will have differing individual physiological and experiential frames of reference and perceptions concerning what features and properties will cause them to perceive softness to a lesser or greater extent.
Various efforts have been made to provide or alter features of nonwoven web materials with the objective of enhancing loft and/or consumer perceptions of softness. These efforts have included selection and/or manipulation of fiber chemistry, basis weight, loft, fiber density, configuration and size, tinting and/or opacifying, embossing or bonding in various patterns, etc. Various approaches are described in, for example, co-pending U.S. application Ser. No. 13/428,404 by Xu et al.
Efforts at enhancing softness attributes and increasing perceptions of softness to date have had varying degrees of success, but have left room for improvements.